Flame retardant urethane forms containing alkanol amino phosphonates

ABSTRACT

Compounds are described which are useful as flame retardants for chemical incorporation into polyurethane and like polymer foams and which have the formula:   wherein R1 and R2 are each hydrocarbyl or halohydrocarbyl, CnH2 n is alkylene (Ca-b) and R3 and R4 taken together with the attached C atom are the residue of a cycloalkane, cycloalkene or cycloalkanone. The compounds have two active hydrogen atoms (marked with an asterisk) which show substantially equal reactivity towards isocyanato groups in sharp contrast to closely related compounds hitherto known. D R A W I N G

United States Patent 1 Smith et al.

[ Sept. 16, 1975 FLAME RETARDANT URE'IHANE FORMS CONTAINING ALKANOL AMINO PHOSPHONATES [75] Inventors: Curtis P. Smith, Cheshire; Henri Ulrich, Northford, both of Conn.

[73] Assignee: The Upjohn Company, Kalamazoo,

Mich.

[221 Filed: Oct. 7, 1974 [21] Appl. No: 512,438

Related US. Application Data [62] Division of Ser. No. 386,520, Aug. 8 l973, Pat. No.

[52] US. Cl. 260/25 AJ; 260/25 AM; 260/775 AQ; 260/775 AR; 260/775 SS [5 l] Int. Cl. C08G 18/32; C08G 18/14 [58] Field of Search 260/25 AJ, 2.5 AM, 77.5 SS, 260/775 AR, 77.5 AQ, 944

[56] References Cited UNITED STATES PATENTS 3,385,9l4 5/l968 Hindersinn 260/944 3480594 ll/l969 Price 260/25 AJ 3,501,421 3/!970 Hindersinn 260/775 AR 3,674,748 7/l972 lliopulos 260/25 AJ 3,855,363 l2/l974 Smith 260/775 AQ Primary E.mminerM. J. Welsh Assislant Examiner-C. Warren Ivy Attorney, Agent, or FirmDenis A. Firth; John Kekich [57] ABSTRACT Compounds are described which are useful as flame retardants for chemical incorporation into polyurethane and like polymer foams and which have the formula:

1 Claim, No Drawings FLAME RETARDANT URETHANE FORMS CONTAINING ALKANOL AMINO PHOSPHONATES BACKGROUND OF THE INVENTION l. Field of the Invention This invention relates to novel phosphonates and is more particularly concerned with novel aminoalkanephosphonates and with polymer foams having said components incorporated therein.

2. Description of the Prior Art A variety of phosphorus-containing polyols has been described for use. in particular. in imparting flame re tardancy to polyurethane foams by including the phosphorus-containing polyol as part of the polyol component which is to be reacted with polyisocyanate in the preparation of said foam. Such phosphorus-containing polyols become chemically incorporated into the polymer backbone. They are therefore preferred over other phosphorus and/or halogen containing fire retardant additives which contain no active hydrogen atom and which. because of this. cannot become chemically incorporated into the polymer and tend to leach out of the resulting foams over a period of time.

One of the most commonly employed class of phosphorus containing polyols is the class of dialkyl di(hydroxyalkyl)aminomethane phosphonates dis closed in US. Pat. No. 3.()76.()|(). These materials are recognized in the art to impart highly significant flame retardant properties to polyurethane foams in which they are incorporated. However. they suffer the disadvantage of exhibiting a tendency to impart hydrolytic instability to the polyurethane and also of being relatively unstable when stored in combination with other polyols employed in the preparation of polyurethane foams. It is common practice to supply two component systems for the manufacture of polyurethanes, one component being a polyisocyanate or an isocyanate terminated prepolymer, and the second component being a mixture of the polyols. surfactants. catalysts and like additives. The two components are stored separately until they are mixed to produce the desired polyurethane. Accordingly, it is highly desirable that any phosphorus-containing polyol employed in such systems be stable on storage in combination with the other polyol components.

US. Pat. No. 3.385.914 describes closely related aminomethane phosphonates which contain at least two active hydrogen atoms. rendering them capable of chemical incorporation into the polyurethane, and which are possessed of improved hydrolytic stability and storage stability in combination with other polyols.

I'ypical of these compounds is dimethyl N-(2- hydroxyethyl )Q-aminopropyl-Z-phosphonate which has the following formula:

II o P NH-(H -(H, ()H (In The two active hydrogen atoms are indicated by asterisks. Unfortunately. it is found that the active hydrogen atom attached to the nitrogen atom in the above molefit] cule has a much greater activity. in reaction with isocy anate groups. than does the active hydrogen atom of the hydroxyl group. So much so that reaction between the above compound and isocyanate takes place almost exclusively via the active hydrogen atom attached to nitrogen and little or no reaction occurs at the hydroxyl group. Hence. the phosphorus containing compound of the above formula tends to act as a chain stopper when employed in the preparation of polyurethane foams.

We have now found a related series of compounds which are free from the above problem but which do possess good hydrolytic stability when incorporated in polyurethane foam. and storage stability when stored in combination with other conventional polyols.

DETAILED DESCRIPTION OF THE INVENTION wherein R and R are each selected from the class consisting ofhydrocarhyl from 1 to [2 carbon atoms. inclusive. and halosubstituted hydrocarbyl from I to l '1 carbon atoms. inclusive;

C,,H- represents alkylene from Z to 8 carbon atoms. inclusive. having at least two carbon atoms separating the valencies; and

R and R taken together with the carbon atom to which they are attached. represent the residue of a cyclic member selected from the class consisting of cyclo alkane. a cycloalkcnc. and a cycloalkanonc. each of said cycloalkane. cycloalkene and cycloalkanone hav ing from 4 to 8 ring carbon atoms. inclusive. and having from (I to 4 loweralkyl substituents.

The invention also comprises polyurethane foams having incorporated therein. as part or the whole of the polyol component used in their preparation. a phosphorus-containing compound of the formula I l.

The term hydrocarbyl from I to 12 carbon atoms. inclusive". means the moiety obtained by removing one hydrogen atom from a hydrocarbon having the stated carbon atom content. Illustrative of hydrocarbyl are alkyl. such as methyl. ethyl. propyl. hexyl. octyl. decyl. dodecyl and the like; alkenyl such as allyl. methallyl. hexenyl. nonenyl, undecenyl. dodecenyl. and the like; cycloalkyl. such as cyclobutyl. cyclohexyl. cycloiictyl. methylcyclohexyl. dimethylcyclohexyl. and the like; cycloalkenyl such as cyclopentenyl. cyclohexenyl. cy cloheptenyl. cycloi'ictenyl. methylcycloheptenyl. and the like; aralkyl such as benzyl. phenethyl. phenylpro pyl. phenylhcxyl. naphthylmethyl. and the like; and aryl such as phenyl. tolyl. xylyl. naphthyl. biphenylyl. and the like.

The term halo-substituted hydrocarbyl from I to II carbon atoms. inclusivemeans hydrocarbyl. as above defined. in which at least one hydrogen atom has been replaced by halo i.e. fluoro, chloro. bromo or iodo. Said halo-substituted hydrocarbyl moieties can contain up to a halo atoms. if desired.

The term alkylene from 2 to 8 carbon atoms. inclusive. having at least two carbon atoms separating the valencies is inclusive of ethyleneml .2propylene. 1.3- propylene. l.2-butylene. l.4-butylene. 2.3-hexylene. l.2-octylene. 3-methyl-l .4pent'ylene. 2-methyl- I .3 butylene. 1.6-hexylene and the like.

Illustrative of cycloalkane having from U to 4 loweralkyl substituents are cyelobutane. methylcyelobutane. cyclopentane. methylcyclopentane. ethylcyclopentane. dimethylcyclopcntane, cyclohexane. isopropylcyclohexane. cycloheptane. methylcycloheptane. trimethylcyeloheptane. ethyltrimethylcyclohexane. cycloiiclane and the like. Illustrative of eycloalkene having from to 4 lower-alkyl substituents are cyclobutene, cyclopentene. cyclohexene, eycloheptene. cycloiictene, mcthylcyclopentene. trimethylcyclopentene. isopropylcyclohexenc. methylethylbutylcyclohexene. tetramethyleyclopentene. and the like. Illustrative of cycloalkanone having from t) to 4 lower-alkyl substitucnts are cyclobutanone. cyclopentanone. cyclohexanone. cyeloheptanone. cycloiictanone. methylcyclopentanone. trimethylcyclohexanone. methylisobutyleycloheptanone. tetramethylcycloiictanone. and the like.

The term loweralkyI" means alkyl from I to 6 carbon atoms. inclusive. such as methyl. ethyl. propyl. bu tyl. pentyl. and hexyl including isomeric forms thereof.

DETAILED DESCRIPTION OF THE INVENTION II A wherein R R R;;. R. and (',,H- are as hereinbel'ore defined. The reaction can be carried out under conditions generally employed in the art as illustrated. for esample. h the reaction conditions described in the aforesaid U.S. Pat. Nos. 3.U7(1.()l() and 3.385.9l4.

Briefly. the reactants are brought together in substan tially stoichiometric proportions in the presence of an inert organic solvent ie a solvent which does not enter into. or in an \va interfere with. the desired course of the reaction. Illustrative of such solvents are alkanols such as methanol. ethanol. isopropanol. and the like. ethers such as diethyl ether. dioxane. tetrahydrol'urane. and the like. and hydrocarbons such as hexane. heptane. octane. bcivene. toluene. cyclohexane and the like. Advantageously. the dih drocarbylphosphate (III) and the alkanolamine (V) are brought together in the inert organic solvent and the ketone (IV) is added to the mixture usually in increments to control the exo thermic rcactionwvhich takes place. The reaction temperature is advantageously maintained in the range of about 40C to about 60C by cooling it necessary and- /or by controlling the rate of addition of the ketone (IV). The resulting product (I) is isolated from the reaction mixture by conventional procedures e.g. b evaporation of the solvent and purification ot' the residue if desired. distillation under reduced pressure (in the case where the product is a liquid). recrystalli zation (in the case where the product is a solid) or by other conventional techniques.

'lhose compounds of the formula (I) wherein the group C,,H has only two carbon atoms between the valencies i.e. wherein C I-I is ethylene or a loweralkyl-substituted ethylene. can be prepared by an alternative method whieh is illustrated by the following scheme:

R (VI) wherein R,. R R and R are as hereinbefore defined and A and B represent hydrogen or lower-alkyl. The compound (VI) is the product obtained by condensing the alkanolamine and the ketone (IV) in the presence of an inert solvent under the temperature conditions discussed. While we believe that the product so obtained is in the form of an oxazolidine represented by the formula (VI) above there is some dispute in the literature as to the nature ol such products. It has been suggested (Bergmann et al. J. A. C. S. 71 .358.1953) that the product is actually an equilibrium mixture of the oxazolidine (VI) and the corresponding imine or Schil'l 's base represented by the formula the proportion of the two components being determined by the nature of the ketone. It is unnecessary to discuss this question in detail here but we wish to make it clear that. whatever the actual fine details of the structure. the compound (\'I) is intended to represent the product otcondensation ol the ketone (IV) and the alkanolamine A II since it is this condensation product. whatever its structure. which is employed in the reaction with the dih drocarbylphosphite (III) in the alternative synthesis of the compounds (I) of the invention.

Ihe dihydrocarbyl phosphite (III the ketones (IV) and the alkanolamines (V) are so well-known in the art. as are methods for their preparation. that it is unnecessary to catalogue such details here.

The novel compounds (I) of the invention are useful in that. when incorporated into polyurethane foams by methods to be described hereinafter. the impart flame retardance thereto. Ihey have the advantage that they can be stored for prolonged periods in combination with other polyol components without causing deleterious effects. they do not rednce the hydrolytic stability of polyurethane foams into which they are incorporated and they possess two active hydrogen atoms of approximately equal activity towards isocyanate groups thus ensuring that they become chemically incorporated without dift'iculty into the polyurethane polymer chain. They do not act as chain stoppers when so used.

The novel compounds (I) of the invention can be incorporated into polyurethane foams simply by replacing at least a part of the polyol employed in the condensation with polyisocyanate in the preparation of said foam. with compound (l). in order to produce significant flame retardancy. the amount of compound (I) in corporated in the foam is generally such that the resultant foam contains at least 1.0 percent by weight of phosphorus. The methods employed in the art to prepare polyurethane foams are so well-known as to need no detailed description here: see. for example. Saun ders et al., Polyurethanes, Chemistry and Technology Part II, pp. 1 298. 1964. lnterscience, New York.

The following examples describe the manner and process of making and using the invention, and set forth the best mode contemplated by the inventors of carrying out the invention. but are not to be construed limiting.

EXAMPLE 1 Di( 2chloropropyl) l-( 2 hydroxyethyl )aminocyclohexylphosphonate A total of 170.3 g. l .74 mole) of cyclohexanone was added with stirring to a solution of 109.8 g. L80 mole) of monoethanolamine in 300 ml. of benzene. The resulting mixture was heated under reflux and the water of condensation which was eliminated was removed continuously by azeotropic distillation using a Dean- Stark trap. The theoretical amount of water (3 l .3 ml.) was removed in 2 hr. At the end of this period the henzene was removed by distillation under reduced pressure. The residue (244 g.) was a golden colored liquid which can be represented by one of the formulae:

or possibly an equilibrium mixture of the two.

A portion (l77.7 g.:l.26 mole) of the above liquid was treated slowly with stirring with a total of 290.6 g. 1.238 mole) of bis(2-chloropropyl )phosphite (Walsh. JACS. 8t, 3023. 1959) over a period of minutes. The temperature was kept below 60C by cooling during the addition. After the addition was complete the resulting mixture was stirred and allowed to cool to room temperature (circa 20C). There was thus obtained 46L) g. of di(Z-chloropropyl) l-(2- hydroxyethyl )aminocyclohexylphosphonate having the formula:

in the form of a clear yellow oil. Analysis: Calcd. for C H NO PCI C, 44.7; H. 7.4; N, 3.7; P. 8.2; CI. 18.8. Found: C. 44.2; H. 7.5; N. 3.6: P. 7.5; CI, l8.4.

EXAMPLE 2 in the form ol'a clear yellow liquid, Anulytix: Calcd. for C H- NO P: C. 5L6]; H, 9.32; N. 5.02; P. ll.l I. Found: C, 5L3); H. 9.64; N. 4.95; P. 10.66.

EXAMPLE 3 Using the procedure described in Example I. but re placing the cyclohexanone there used by an equivalent amount of isophorone (3.5.54rimethyl-Z- cyelohexenone the re was obtained di( 2- chloropropyl) HZ-hydroxyethyl ]-amino-3.5.5- trimethyl-Z-eyclohexenyl-phosphonate having the formula:

Similarly. using the procedure described in Example I. but replacing cyclohexanone by an equivalent amount of cyclopentanonc. 2.2.4.4-tetramethylbutanedione-L}. Z-cycloheptenone. or cycloiietanone. there was obtained:

di( 2-chloropropyl) hydroxyethyl )aminocyclopentylphosphonatc.

7 di( Z-chloropropyl) l-( Z-hy droxyethyl )amino 2.14.4-tetramethylcyclobutan-3-onylphosphonate di( Z-chloropropyl) l-t 2-hydroxyethyl )aminwl cycloheptenylphosphonate; and di( 2-chloropropyll hydrosyethyl )aminoc ycloi'ictylphosphonatc. spectively.

EXAMPLE 4 l-( Q-hydroyycthyl laminoe ycloheyyl- EXAMPLE 5 A mixture of 74 g. t l mole) of isopropanolaminc. I38 g. mole) of diethyl phosphite and 200 g. 1.4 mole) of anhydrous sodium sulfate in ZUU ml. of henzene was stirred while a total of )8 g. l l mole l ofcyclohcyanone was added. The mixture was cooled when necessary to maintain the reaction temperature below about 50%. After the temperature subsided the mixture was stirred for a further 3 hours and then filtered. The filtrate was c\ aporated to dryness. There was thus obtained diethyl l( Z-hdy royypropyl )aminocyclohex \lphosphonate.

Similarly. using the abo e procedure. but replacing the isopropanolamine by propanolaminc. hexanolamine. octanolamine. l-hydroxyhe ylamine and 4- hy dro\ y-Z-oet \lamine. there was obtained:

diethyl l 3-h dro\y propy l laminocy clohe.\ ylphosphonate diethyl l-t b-hydroxyhesyl )aminocycloheyy lpliosphonate octyl |aminocyelo|ie\ \lphosphonate. respecti ely.

EXAMPLE previously phosphitc. acetone and ethanolamine using the procc dure described in Example I l.

A solution of 3.5 g. ((LUUU} mole) of di(:- chloropropyll l-[ Z-hy droyy ethyl )aminocycloheyy I- phosphonate in 50 ml. of anhydrous beniene was ad mixed. with stirring. with l l: ml. HLUUH mole) of phenyl isocyanate. The progress of reaction was followed by infrared spectral analysis of aliquots. it was found that. over a period of 5 hours, the absorption band corresponding to isoeyanate gradually disappeared while absorption bands corresponding to forma' tion of urethane (5.80 a) and urea (5.96 pi) were formed at substantially equal rates.

in contrast. when the above procedure was repeated using a solution of 3 g. (0.008) mole) of di(]!- chloropropyl) 2-( Z-hyd roxyethyl )amino-Z- propylphosphonate in 50 ml. of anhydrous benzene, to which was added I ml. of phenyl isoeyanate. it was found that the absorption band corresponding to isocyanato disappeared within a very short period (30 minutes) and a very strong band at 6.0 p. (urea) appeared within the same time period. Even after 6 hours of reaction there was no detectable band at 5.8a (urethane). However, when a second I ml. portion of phenylisocyanate was added the absorption band at 5.8a slowly appeared.

The above experiments indicate that, in the case of di( 2-chloropropyl) l-( 2- hydroxylethyl )aminocyclohexylphosphonate the active hydrogen atoms attached to nitrogen and to oxygen reacted with isocyanate at substantially the same rate. In the of di( Z-chloropropyl) 2-( 2- hydroxycthyl)amino-'l-propylphosphonate the active hydrogen atom attached to nitrogen reacted with isocyanate to the complete exclusion of reaction with the ae tive hydrogen atom attached to oxygen. Only when all the active hydrogen attached to nitrogen had reacted i.e, after 1 molar proportion of isocyanate had been used and a second such portion added. did any reaction occur at the active hydrogen atom attached to oxygen.

LIHSC EXAMPLE 7 Rigid polyurethane foams were prepared using a standard formulation in which 25% by weight of the polyol component was replaced by the compound of iixamplc l. and. for comparison purposes. by the compound dicthyl di(Z-hydroxyethylIaminomethanephosphonate lFy rol (1], The formulations (all parts by weight) and physical properties of the two foams are recorded in l'able 1. ln both cases the polyols. surfactant. catalyst and water were blended. the freon was added. and finally the polyisocy anate was admixed with high speed stirring for l5 seconds. The resulting mixture was allowed to foam freely in a paper cup and the foam so obtained was cured in air at room temperature (circa Ztl() for 3 days.

it will be seen that the foam (Foam A) prepared using the phosphorus containing diol of Example 1 had superior physical strength properties and markedly less shrinkage on humid aging than did the foam [Foam Bl prepared from the known phosphorus compound.

I able l Table l-Continued Foam A Foam I! PROPERTIES Density. pcf. .55 2.92 Compressive strength psi lo rise 58.8 27!) perpendicular to rise 27.8 I714 96 volume change on humid age at l5RF and Hlllll humidit) l day 16 9 3 days 4.6 I41 7 days 6.4 11.0 14 days L3 l L! '1 volume change on dr aging at 200F l day 0 an 7 days ll) 25 Futilnnlcs to 'I'ABLF l Blend ul li polyil obtained h l1l'll|fll\ \kllil'll a pol mellnlenc pol phenyl pobamine containing alppnuimalcl 50'; diamine and (ii) the :aklucl nl ghcerul and promlcnc oxide teq. wt. N! I.

()rganosilicone [X'- W].

whcrein R and R are each selected from the class consisting ofhydrocarhyl from I to 12 carbon atoms. inclusive. and halo-substituted hydrocarhyl from I to l 2 carbon atoms. inclusive;

( H- represents alkylenc from 2 to 8 carbon atoms. inclusive. having at least 2 carbon atoms separating the valencies; and

R and R taken together with the carbon atom to which they are attached. represent the residue of a cyclic member selected from the class consisting of cycloalkane. a cycloalkcne and a cycloalkanonc each of said cycloalkanc. cyeloalkenc and c cloalkanone having from 4 to 8 ring carbon atoms. inclusive. and having from U to 4 lowcr-alkyl suhstituents.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent 0 3 Dated September 16, 1975 Inventor) Curtis P. Smith and Henri Ulrich It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

[57] Abstract: That portion of the formula shown as C- H Should read C H [57] Abstract: Should read:

alkylene (C alkylene (C Column 1, Lines 60 65: That portion of the formula shown as lCH i31 C Should read IC CH CH3 Column 2, Lines 21 26: That portion of the formula shown as Should read -l- (continued) 3,905,922 d September 16, 1975 Patent No. Date lnventofls) Curtis P. Smith and Henri Ulrich It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 3, Lines 33 38:

The formula IO should read IO l I C C 4 1 a 4 Column 4, Lines 9 14: That portion of the formula shown as C should read C R R R R Column 4, Lines 36 40: That portion of the formula shown as C= should read C= R 12 Column 4, Lines 50 52:

The formula A F should read F 11 CH CH CH MH CHCH-OH Column 9, Table I, Line 6: Should read:

to rise to rise -2- (continued) UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No- 3|9O5|922 Dated September 16, 1975 Curtis P. Smith and Henri Ulrich Inventor(s) It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 10, Claim 1, Lines 1 6: That portion of the formula shown as should read Signed and Scaled this sixth D y of January 1976 [SEAL] Arrest:

RUTH C. MASON C. MARSHALL DANN Arresting Officer Commissioner of Parents and Trademarks 

1. A FIRE RETRDANT POLYURETHANE WHICH COMPRISES THE PRODUCT OF REACTION OF A POLYOL AND A POLYISOCYANATE UNDER FOAM PRODUCING CONDITIONS CHARACTERIZED IN THAT AT LEAST PART OF SAID POLYOL COMPRISES A COMPOUND HAVING THE FORMULA: 